1. Field of the Invention
The present invention relates to the manufacture of silicon microstructures and, more particularly, the fabrication of porous silicon having radiative properties and useful in optoelectronic devices.
2. Description of the Related Art
Porous silicon can emit light. The use of porous silicon in light emitting diodes is presently being investigated. This light emitting characteristic has been demonstrated in etched porous silicon. The etching has conventionally been done by electrochemical etching. However, the conventional electrochemical etch is highly non-uniform and non-repeatable.
Electrochemical and chemical dissolution steps have been used to fabricate free-standing quantum wires out of bulk silicon wafers. Porous silicon layers having a pore width of 20-500 .ANG. were reported to exhibit red photoluminescence at room temperature. Silicon wafers were anodized at low current densities in hydrofluoric acid-based solutions in order to generate an array of extremely small holes that run orthogonal to the surface of the substrate. See, "Silicon Quantum Wire Array Fabricated by Electrochemical and Chemical Dissolution of Wafers", Appl. Phys. Lett., Vol. 57, No. 10, Sep. 3, 1990. See also, V. Lehmann et al., "Porous Silicon Formation: A Quantum Wire Effect", Appl. Phys. Lett., Vol. 58, No. 8, Feb. 25, 1991.